The objective of this contract is to develop a system to enroll and follow hemophilic patients who are infected with the human immunodeficiency virus (HIV) into clinical trials to determine the long term safety and efficacy of Zidovudine (ZDV, also known as Azidothymidine or AZT). Safety of ZDV will be assessed by close clinical laboratory monitoring of the patients for toxicity. Efficacy will be based on a) following the hemophilic patient to determine the rate of development of the acquired immunodeficiency syndrome (AIDS), the rate of detecting virus or virus-coded products, and the effects on the immune system; and b) following the spouses of the hemophilic patients participating in the study to determine the effects of therapy on transmissibility.